RVO reported that Manam's Southern Crater continued to erupt during 1-15 October. Activity was low the first few days, characterized by emissions of light gray ash plumes, occasional dark gray plumes, and ejected incandescent tephra. The intensity of ejected incandescent tephra increased on 5 October, and peaked during 9-10 October when the ejections developed into Strombolian activity. Strong explosions during the Strombolian activity produced shock waves that rattled houses on the S part of the island. Activity subsided after 10 October; erupted material fell in the SE and SE valleys. There was a corresponding increase in emissions of ash clouds that drifted NW but the volume of ash appeared insignificant. White vapor plumes rose from Main Crater during the reporting period.

Based on analyses of satellite imagery, the Darwin VAAC reported that on 15 October an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 37 km SW.

Geological Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Sources: Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC)